William m



' datrtl "tstre @sind @time g Letters Patent No. 96,499, dated November 2,1869.

vBAII'JAIICII] SLIDE-VALVE.

The Schedule referred to in these Letters Patent and making part of the same,

declare the same to be f'ully described lin thc tbllowing.

specification, and represented in the accompanying drawings, of which- Figure l is a vertical section of a' steam-chest ,and-

the valve thercoi',as provided with my invention; Figure 2 is a transverse section of the same; lfignre 3 is a top View ;v and Figure 4, a bottom view ot' the valve. ln carrying out. my invention, I provide thc slidevalvc with extra walls and a chamber between eachV main wail and its next adjacent extra wall, and over each ofthe chambers l'arrange another long chamber or groove, and place therein two triangular prisms, ortheir equivalents, arranged in manner as represented in thc drawings. l also open a. slit or passa-ge through thc bottom ot' each oi' thc said chambers.

lhe :ulditional'wail to each` main wall of' the valve may be arranged .on either side oisuch wall, the extra wall being extended sonicwhatbcyond the port-lap, or flange for covering a port.

In the. drawingl- A denotes the steam-chest, constructed in the usual manner, and with two iluluction-ports, C C, and one cduclion-port, l), lea-ding out oi' the lower valve-seat, or bottom oi'the chest.

The two main walls of the valve are shown ata (t, their port-laps or lianges being represented at b b.

The. auxiliary walls, denoted at ft' a', are parallel, or about so, to the main walls, with a chamber, B, between each t-wo walls (l. a'.

There is au opening or space, c, at the bottom of -eacb chamber B-,and there are other openingsl or holes,

d, made through the top of such chamber, so as lto lead into an auxiliary packingfchainber oi; groove, E, arranged directly over the chamber B, and with respect to another parking-groove, F, in manner as represented. .lhis latter groove extends around the whole valve, at its top, and carries a packing composed oi' a series ot' bars,.j, oi' metal.

Holes y, made through the outer sides of the lastmentioned lacking-groove, F, serve to let steam pass from the chest into the groove in order to force its packings up to thc top ot' the chest.

Within each of the grooves E there are placed two right-angled triangular prisms or packings, li- It, which are arranged with their hypothenusal sides in Contact.

When the steam passes up through the passages l (I, it will act against the lower of the two strips hhl, and ibrce it and the upper one upward, so as to crowd the latter up against the capot' the steam-chest, thereby sealing the valve at top, so as to prevent; the escape of steam over the valve.

While passing across a port, the port-lap will be subjected to an upward pressure of' the. steam, andthe steam will flow into the chamber B, and thence into the groove E. The steam, by acting against the bottom ofthe groove, and also thc bottom oi' the packing thereof, will counterbalance the said upward pressure on the port-lap. 'lhe triangular prisinatic packingstrips, by being pressed against one another, willbe moved laterally in opposite directions, against the sides of their groove, so as to make close jointstherewith.

The valve is chambered, as shown at s, and is, as shown at t, openat top, and at bot-tom, as shown at u, in consequence of which, the exhaust-steam, after escaping into the middle chambers, will strike directly against the cap 'of the steam-chest, and thus does not act to produce any upward pressure, tending to force the valve ott' its sea-t, as would result were the chamber s ot' the valve closed lat top, as in other balance-valves.

I herein make no claim toa balance-valve constructed with a cavity between its walls, with packing-strips and grooves for their reception at' the upper portions of the walls, and with one or more passages leading out of each ot' such. grooves, so as to open into the steam-chest,'such heilig as shown in Letters Patent No. 83,336, dated October 20, 1868, and granted to What I claim, as my present invention, is as folf lows:

The arrangement andcombination of the two cha-nb, bers B B, their packing-grooves E E, packings h, and openings c tl, with the balance-valve, having the cham-.

v ber s open at top and hottoni, and the grooves F and their vpacltings f, the whole being substantially as de.- scribed. y

WM. M. STEVENSON.

Witnesses R. H. EDDY, J R. Snow. 

